The present invention relates to a coil holder for one or several coils arranged one after the other.
For obtaining a high winding speed, the coil holder must have a maximum possible rigidity. These requirements can be satisfied only with a suitable clamping system.
The German document DE-C 30 39 064 discloses a clamping chuck in coil machines for receiving a coil support, a rotatable clamping mandrel, a casing with throughgoing openings for radial passage of a corresponding clamping element, a plurality of clamping elements, and displacing elements arranged in the intermediate space between the clamping mandrel and the casing for displacing the clamping element, as well as a part of a device for displacing the displacing element. The clamping elements are provided with the surfaces which are wedge-shaped in an axial direction. Along these surfaces, they are axially displaceable on corresponding counter surfaces of the displacing element and thereby simultaneously move radially. The clamping is performed by a device for displacing the displacing element with springs which act on the displacing elements and are compressed for unclamping by pressure air.
In the construction disclosed in this reference, the rigidity of the coil holder is determined by the clamping mandrel. A high rigidity of the coil support requires a predetermined diameter of the clamping mandrel. Since relatively great space is needed for the intermediate space with the clamping elements and means for displacing the clamping elements and the casing, the outer diameter of the clamping mandrel is small relative to the inner diameter of the coil to be clamped. A high rigidity of the coil holder is therefore not obtained with this system.
The German Document DE-B 27 19 853 described a coil holder with a rotatable main pipe, a casing sleeve provided with openings for clamping elements and with clamping elements arranged therebetween, cages for radial movement of the clamping elements and a part of a device for moving the cages, which however is not suitable for high winding speeds. This reference also discloses the use of cylindrical rollers which have axes extending parallel to the rotary axes and are formed as clamping elements.
The German Patent Document DE-A 43 35 258, DE-A 43 35 259 and DE-A 30 44 315 disclose coil holders with supporting pipes which increase the rigidity of the coil holders. These supporting pipes are provided with throughgoing openings for clamping elements. The clamping elements, as disclosed for example in the patent document DE-A 43 35 258, are distributed in groups uniformly on an outer peripheral line of the supporting pipe and arranged so as to move radially outwardly. Elements for moving the clamping elements are located inside the supporting pipe, and an axial displacement on the wedge surfaces leads to a radial displacement of the clamping element. The clamping device disclosed in the German document DE-A 43 35 258 performs the clamping and unclamping by means of a spring force and the pressure air, the clamping system described in the patent document DE-A 43 35 259 performs the clamping and unclamping by means of a central threaded rod, and the clamping device disclosed in the German patent document DE-A 30 44 315 performs the clamping and unclamping by means of a flat pulling rod.
In these coil holders, the rigidity with the predetermined outer diameter of the coil holder or in other words the supporting pipe is still low. For obtaining a greater rigidity, a predetermined wall thickness of the supporting pipe is needed. This is true especially since the supporting pipes are provided with many openings for the clamping elements. Moreover, a certain space for the means for displacing the clamping element inside the supporting pipe is needed.
The European patent document EP-A 06 36 565 discloses a coil holder with higher rigidity. The coil holder has a rotatable main pipe which determines the rigidity and is provided with axially arranged ring-shaped recess. Clamping elements are distributed on a peripheral line in the recesses and are inserted with a part in the recesses. Here also a radial displacement of the clamping element is performed by an axial displacement on wedge-shaped surfaces. In this reference, the web-shaped surfaces are formed by the clamping elements and the supporting surfaces of the recess. The axial displacement of the clamping elements is performed by means of displacing sleeves which are arranged on the main pipe axially one behind the other and for example connected with one another. They are provided with openings for the clamping elements. The clamping is performed by means of a spring force, and in addition to the spring arresting the displacing sleeve, a spring is provided with each clamping element.
A further coil holder in which the clamping elements are partially arranged in the recesses of a main roll is disclosed in the German document DE-A 21 06 493. The wedge-shaped supporting surfaces of the recesses of the main pipe extend in a peripheral direction. For a radial movement of the clamping element, a basket surrounds the main pipe and is provided with openings, to hold the clamping element by prestressed springs in the clamping position. In this coil holder the main pipe is weakened by recesses which extend a circumferential direction and occupy approximately 90% of the periphery, as well as by further recesses for the springs which prestress the cage. The coil holder does not have a sufficient rigidity to be used with high winding speeds. Moreover, in this clamping system a reliable, fast acceleration and breaking is not guaranteed.